Keith is saving money for a car. He has saved the same amount each year for the past three years, and records how much he has at the end of each year in the table below.
Year 1Year 2Year 3
Total amount saveddollar sign, 1500dollar sign, 3000dollar sign, 4500
What is Keith's unit rate of change of dollars with respect to time; that is, how much does Keith save in one year?
The unit rate is
  • Your answer should be
  • an integer, like 6
  • an exact decimal, like 0, point, 75
  • a simplified proper fraction, like 3, slash, 5
  • a simplified improper fraction, like 7, slash, 4
  • a mixed number, like 1, space, 3, slash, 4
dollars per year.
Graph the proportional relationship described above, with the x-coordinate representing years, and the y-coordinate representing amount saved in thousands of dollars.